And I'm Renee Montagne. The nation's oil and natural gas booms come with some environmental challenges. One of those is air pollution from equipment leaking gas that contributes to smog and climate change. Colorado just approved the nation's first-ever regulations of methane, a potent greenhouse gas. As NPR's Elizabeth Shogren reports, some energy companies stepped up in hopes that tough new regulations would counter growing public resistance to their industry.

ELIZABETH SHOGREN, BYLINE: Colorado estimates that its new rules will cut tens of thousands of tons of pollution each year.

DR. LARRY WOLK: And just to put that into perspective, that's equivalent to taking all the cars off the roads of the state of Colorado for an entire year.

SHOGREN: Dr. Larry Wolk is the executive director of Colorado's Department of Public Health and Environment. He says the rules will help his state clean up its smog problem and fight climate change. Three of Colorado's largest drilling companies helped craft the rules. Dan Grossman from Environmental Defense Fund worked with the companies to come up with the rules.

DAN GROSSMAN: Natural gas is a resource that offers some promise from a climate change perspective. When you burn it, it's a lot cleaner than other resources such as coal.

SHOGREN: U.S. greenhouse emissions are dropping as the country uses more natural gas and less coal for electricity. But Grossman says there's a hitch.

GROSSMAN: If you have a lot of leaky oil and gas operations in the state, then you offset the benefits of burning natural gas versus coal.

SHOGREN: The oil and gas sector is the nation's largest source of methane emissions. Methane leaks from wells, storage tanks and other equipment. Methane is a potent greenhouse gas. It traps heat in the atmosphere even more than carbon dioxide does. That's why Colorado's new rules are important. They require companies to seek out leaks and fix them. Doug Hock represents one of the participating drilling companies, Encana.

DOUG HOCK: Generally what you use is an infrared camera. That allows you to see leaks in valves and equipment that are not visible to the naked eye.

SHOGREN: Companies have a variety of incentives to fix leaks. Methane essentially is natural gas.

HOCK: You know, that's the product that we produce. Those are dollars that are going into the air, literally.

SHOGREN: But that's not the only reason Colorado's biggest oil and gas producers went for the nation's toughest air pollution rules. Ted Brown is a senior vice president of Noble Energy.

TED BROWN: It's all about a social license to operate.

SHOGREN: Brown hopes that these rules, will help show that his industry can help the country reduce greenhouse gas emissions.

BROWN: If we're going to compete on a climate change type of fuel versus coal, we really needed to start with methane.

SHOGREN: But there's a local message too. In the last couple years five different communities in Colorado have passed bans on hydraulic fracturing. That's the drilling technique that's fueling the big expansion of oil and gas. Dan Grossman from the Environmental Defense Fund says public resistance helped bring the companies into the negotiations.

GROSSMAN: That consternation I think really wore down industry to the extent where they really thought a good victory like this could help build confidence in the public.

SHOGREN: But that public resistance hasn't stopped. The groups that fought against fracking want to see more scientific research. Kelly Giddens is president of Citizens for a Healthy Fort Collins.

KELLY GIDDENS: We knew that industry would feel that way. But the truth is, is that we don't really know those regulations go far enough, and our real question is why should we allow these companies to move forward if we don't have the data that proves that fracking is safe?